The primary objective of this investigation is to study the mechanism of RNA biosynthesis in Escherichia coli and in bacteriophage-infected E. coli. The major emphasis during the current project period will be on the structure, function and mechanism of action of the rho transcription termination protein. The enzymatic properties of the RNA-dependent ATPase activity of rho will be studied. This will include an analysis of the kinetics of the reaction, the effects of inhibitors and the minimum requirements for an RNA to activate the ATPase activity. An attempt will be made to define the role of th ATPase reaction in the termination of RNA synthesis catalyzed by RNA polymerase. The mechanism of rho action in termination will be investigated in detail using T7 DNA and specific restriction endonuclease-generated fragments of bacteriophage lambda DNA that code for the synthesis of a single RNA transcript that can be terminated by rho action. Mutants with defects in rho will also be used to study the effects of inactivation of rho factor on RNA metabolism in vivo.